Singing diff

[steround]

I've been told today that my 1997 C200 may have a 'singing diff'.

Can anyone tell me how much this will cost?

Is it essential to fix it?

 

[wingco]

I had a c250TD which developed a whining noise. I had tthe diff rebiult by a transmission specialist from memory:

500 quid if its just the bearings (parts and labour)

900 quid if the crown wheel and pinion have gone as well (parts and labour)

Silly money if the stealership do it.

On mine it was just the bearings and I had it done at 130k. I am not sure what happens if you don't get it repaired.

 

[Glenn Smith]

I've been told today that my 1997 C200 may have a 'singing diff'.

Can anyone tell me how much this will cost?

Is it essential to fix it?

Change the oil first, a good additive may also quieten it down, if it's bothering you. I had a noisy diff in a golf gti, i changed the oil and drove another 80000 miles in it and never heard it again, so it's worth a go.
How many miles has your car done?

 

[television]

If the pinion is riding the crown wheel out of mesh, the long term may mean a new crown wheel and pinion as once the gear are damaged, no bearings can put this straight.

The bearings do solve it 95% of the time, find a diff / axle rebuilder.

Where do you live ?

 

[daveenty]

There is a Merc indie (MercStar) in Radcliffe. Can't remember the address, but they're in between the Town Hall and Ainsworth Road (same side)

I've never used them.

There is also another one in Whitefield (Greenvale Mercedes) who one of the senior members on here does praise. (Parrot of Doom)

May be worth asking one of them as they *may* have either a spare differential or even the bits to fix yours?

 

[television]

There is a Merc indie (MercStar) in Radcliffe. Can't remember the address, but they're in between the Town Hall and Ainsworth Road (same side)

I've never used them.

There is also another one in Whitefield (Greenvale Mercedes) who one of the senior members on here does praise. (Parrot of Doom)

May be worth asking one of them as they *may* have either a spare differential or even the bits to fix yours?

Another diff as you say could be the answer, sadly the art of re building diffs is dying fast, it is a specialist job and very engineers left who can do this, you have to understand how to blue the gears and be sure the the mesh is taking place on the correct part of the gear. I did that in 1950, plus I did the one on my RR.

 

[greenfingers]

I would try Glenn Smith's suggestion of new oil and additive before spending big money.

If you have a whine that increases in pitch with road speed, then it suggests worn gearwheels. My old Reliant Scimitar did this until I changed the fluid and injected a PTFE additive (Nulon) - never heard it again.

I suspect that a worn bearing will cause a hiss, rasp or rumble, depending on how far it has deteriorated. In this case catastrophic failure could be around the corner. Don't think this is your symptom as you used the term singing.

Another method of DIY diagnosis is to go for a short drive, then feel the temperature of the diff with your hand. If the driveshaft/propshaft areas are warmer than the rest, this would indicate bearing trouble.

 

[television]

The correct way to diagnose the diff is if it whines when you are pulling and is quite on the over run, then it is the pinion bearing

 

[jibcl500]

Also be sure the prop bearing isnt at fault !!!!

jib

 

[greenfingers]

Quote: 'whines when pulling, and quiet on overrun'

I will stand down if proven wrong, but surely regardless of whether the bearing or gearwheel is shot, the load is only applied when under power, so the symptoms are only evident when accelerating?

 

[television]

Quote: 'whines when pulling, and quiet on overrun'

I will stand down if proven wrong, but surely regardless of whether the bearing or gearwheel is shot, the load is only applied when under power, so the symptoms are only evident when accelerating?

That is what I said, whines when pulling, quiet when you take your foot off

 

[daveenty]

Be nice to hear what the OP has done about this

I only live around the corner (well, nearly)

Will this be another one post wonder?

 

[wireman]

Greenfingers, when on you release the throttle the vehicle will slow due to engine braking, the engine becomes the load and the prime mover is the car i.e. the load is applied in the opposite direction but its still a load.
As a rough guide, if the crownwheel or pinion are worn there will be excess play in the input flange, you will be able to twist the propshaft (in neutral) through a wider angle if this is the case, a millimetre or two on the flange will probably be OK, maybe someone has a real measurement for you to compare.

There are several bearings in the diff assy, the pair of taper roller bearings on the input shaft (pinion) and another pair one either side of the complete diff assy again usualy taper roller, they are both mounted in some form of axialy (end to end) adjustable fixture of spacers and ring nuts or the like to allow manufacturing tolerances to be eliminated from the assy.

I have found the nut inside the drive flange slightly loose on several cars (escorts viva and capri) causing them to whine and slightly clonk, it may not be so on yours but may be worth a check.
As others say they are a bit difficult to setup you need some fancy tools and a very clean work space it is only DIY for the very keen, the lowest cost may be a salvaged unit from the breakers.

 

[greenfingers]

Greenfingers, when on you release the throttle the vehicle will slow due to engine braking, the engine becomes the load and the prime mover is the car i.e. the load is applied in the opposite direction but its still a load.
As a rough guide, if the crownwheel or pinion are worn there will be excess play in the input flange, you will be able to twist the propshaft (in neutral) through a wider angle if this is the case, a millimetre or two on the flange will probably be OK, maybe someone has a real measurement for you to compare.

Ok, so the back of the lobes take a small load when decelerating, but the wear is on the front of the lobes (from accelerating). When the gears are worn, certainly there will be evidence of backlash, and the resulting 'pressure angle' causes increased friction, wear and noise.
You will see the same effect if you look at a used motorcycle chain sprocket.

In theory, wear on the bearing races could compensated for by adding shims or cranking up the pinion torque, but my original point was intended to suggest that worn gears rather than bearings were the problem.

 

[television]

you can push this around all you like but that the fact is when the pinion bearing has gone the diff will whine when pulling/driving from around 30mph and up , and when you take your foot off the throttle it stops whining, its been like this since I have stated driving, and thats a long time.

If left too long the crown wheel can be damaged beyond repair

 

[steround]

Thanks for the suggestions folks.

Daveenty, I used to live in Ramsbottom myself.

A few more details.

I can hear it at 20mph, and it increases in pitch slightly as I gather speed up to 60mph, then it gets quieter.

If I turn to the left it stops.

The car has done 136k miles.

Greenvales serviced it for me about 6 weeks ago, and I was really impressed with them. I'm taking it to them this week.

Merc-star are very good as well, but a bit steep on the labour charges.

Greenvales diagnosed the diff, but the guy also said it may be a rear wheel bearing.

 

[jibcl500]

Sounds to me like prop center bearing, starts whining at 20-30 all the way upto 60 ish and then its nice and quiet. Diffs tend to make a noise regardless of speed.

I assume its not that noticable if your have the radio on etc,

jib

 

[steround]

Yep, thats how I currently fix it, just turn the radio up....